Deck Height, Guards, and When a Permit Usually Appears

Deck conversations collapse to height faster than homeowners expect. Square footage prices the lumber. Height above finished grade decides guards, stairs, and — in many cities — whether a permit exists at all.

Thirty inches is a pattern, not a national law

Model residential codes have long used a walking-surface height of more than 30 inches above grade as a trigger for guards. Many U.S. cities have adopted some version of that idea. Your city may use a different number, or it may require a permit for any attached deck regardless of height. Measure from finished grade to the walking surface, not to the joists.

Attached vs. freestanding

A ledger screwed into the house is a structural connection and a flashing problem. Lateral tension ties exist because decks have left the house in high-wind and seismic events. Freestanding decks still need footings below frost in cold climates. “Floating” is a product word, not a code category.

Size the platform with the deck calculator.